Thermomechanical Effects Associated With Crystallization of Rubber Under Stretch and During Slow Extension

1997 ◽  
Vol 119 (3) ◽  
pp. 298-304 ◽  
Author(s):  
Mehrdad Negahban

A natural rubber sample which crystallizes after stretching normally shows stress relaxation associated with this crystallization and normally ends up at a stress lower than that of the fully amorphous rubber before crystallization. On the other hand, a natural rubber sample which crystallizes during stretching becomes more rigid as a result of the crystallization and the stress required to extend it to a given stretch increases substantially above the stress needed to extend the fully amorphous rubber to the same elongation. Even though the former effect has been modeled and studied by the likes of Flory (1947), the latter effect has not yet been properly modeled or studied. The difference between crystallization during or after stretching will be studied in this article based on a thermodynamic model developed by the author to capture the thermomechanical effects of crystallization in natural rubber. The two limit cases of very rapid and very slow extension to a given stretch are singled out for comparison of the equilibrium stress.

1949 ◽  
Vol 22 (4) ◽  
pp. 994-999
Author(s):  
G. T. Verghese

Abstract Considerable data on the vulcanization characteristics of molecular fractions of ordinary (unpurified) natural rubber are available. There is, on the other hand, little information of any systematic work on the vulcanization of purified rubber and of its fractions. Pummerer and Pahl vulcanized the sol and gel fractions obtained from purified Hevea rubber, and also the purified whole rubber. But apart from a statement that whole rubber vulcanized much faster than the two fractions obtained from it, no details have been published. Vulcanization of purified whole rubber and of its sol and gel fractions was studied also by Smith and Holt. They concluded that the difference which they observed in the stress-strain behavior of the fractions and whole rubber was due to differences in the rubber which persisted through vulcanization. The present paper deals with a study of the vulcanization characteristics of different fractions of purified rubber prepared by a method described in a previous paper. Also, for comparative purposes a similar study was made of the corresponding fractions of unpurified rubber. As the difference in molecular weight of some of the fractions obtained by the above method was rather small, a grouping of the fractions was made as follows :


1995 ◽  
Vol 68 (1) ◽  
pp. 124-131 ◽  
Author(s):  
P. G. Santangelo ◽  
C. M. Roland

Abstract When measured parallel to the curing deformation, double networks of natural rubber have a higher modulus than single networks of equal crosslink density. The difference is greater at higher strains. Despite the higher modulus, the mechanical fatigue lifetimes of double networks were found to be as much as a factor of ten higher than for conventionally crosslinked NR. The double network's tensile strength, on the other hand, was slightly lower. In contrast to these results, the modulus and tensile strength in the direction transverse to the curing strain are minimally affected by the presence of a composite network.


Open Theology ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 430-450
Author(s):  
Kristóf Oltvai

Abstract Karl Barth’s and Jean-Luc Marion’s theories of revelation, though prominent and popular, are often criticized by both theologians and philosophers for effacing the human subject’s epistemic integrity. I argue here that, in fact, both Barth and Marion appeal to revelation in an attempt to respond to a tendency within philosophy to coerce thought. Philosophy, when it claims to be able to access a universal, absolute truth within history, degenerates into ideology. By making conceptually possible some ‚evental’ phenomena that always evade a priori epistemic conditions, Barth’s and Marion’s theories of revelation relativize all philosophical knowledge, rendering any ideological claim to absolute truth impossible. The difference between their two theories, then, lies in how they understand the relationship between philosophy and theology. For Barth, philosophy’s attempts to make itself absolute is a produce of sinful human vanity; its corrective is thus an authentic revealed theology, which Barth articulates in Christian, dogmatic terms. Marion, on the other hand, equipped with Heidegger’s critique of ontotheology, highlights one specific kind of philosophizing—metaphysics—as generative of ideology. To counter metaphysics, Marion draws heavily on Barth’s account of revelation but secularizes it, reinterpreting the ‚event’ as the saturated phenomenon. Revelation’s unpredictability is thus preserved within Marion’s philosophy, but is no longer restricted to the appearing of God. Both understandings of revelation achieve the same epistemological result, however. Reality can never be rendered transparent to thought; within history, all truth is provisional. A concept of revelation drawn originally from Christian theology thus, counterintuitively, is what secures philosophy’s right to challenge and critique the pre-given, a hermeneutic freedom I suggest is the meaning of sola scriptura.


1974 ◽  
Vol 26 (2) ◽  
pp. 189-195 ◽  
Author(s):  
Irene Klenbort ◽  
Moshe Anisfeld

The subjects were presented with active and passive sentences. For each sentence, they had to choose between two alternative implications. The pattern of choices indicates that in the passive the logical subject was interpreted by the subjects as the focal point of the information asserted by the sentence and as the carrier of overall responsibility for the sentential proposition. In contrast to the passive, there was no clear pattern of preferences for the active. The difference between the two voices was attributed to their markedness asymmetry, the passive being marked and the active unmarked. It is concluded that the active offers a neutral structure for conveying information; a structure available for use when one does not want to superimpose on the information content any stylistic or connotational implications. The passive, on the other hand, suggests special connotations in addition to the basic message.


2021 ◽  
Vol 29 (1) ◽  
pp. 36-61
Author(s):  
Michael Poznic ◽  
Rafaela Hillerbrand

Climatologists have recently introduced a distinction between projections as scenario-based model results on the one hand and predictions on the other hand. The interpretation and usage of both terms is, however, not univocal. It is stated that the ambiguities of the interpretations may cause problems in the communication of climate science within the scientific community and to the public realm. This paper suggests an account of scenarios as props in games of make-belive. With this account, we explain the difference between projections that should be make-believed and other model results that should be believed.


2006 ◽  
Vol 21 (3) ◽  
pp. 112-117
Author(s):  
Shinichi Furuya ◽  
Hidehiro Nakahara ◽  
Tomoko Aoki ◽  
Hiroshi Kinoshita

The purpose of this study was to investigate the prevalence of playing-related musculoskeletal disorders (PRMDs) among Japanese female classical pianists of different age groups. The causal factors for PRMDs also were examined. A group of 203 senior pianists, including piano teachers and students with piano majors at high schools and colleges, were surveyed using questionnaires. Results showed that 77% of these pianists suffered from PRMDs in at least one of their body portions. This value was larger than those reported in Western countries. Forty-four percent of these were serious enough to warrant medical treatment, which was a lower rate than reported in Western countries. The difference in these numbers may reflect the current state of understanding of PRMDs among Japanese pianists and their educators. The prevalence of PRMDs was found to be age-dependent. In the student groups, the finger/hand had the highest rate of PRMDs, followed by the forearm and shoulder. The senior group, on the other hand, had the highest PRMD incidence at the neck/trunk, followed by the forearm and hand/finger. Care may need to be exercised for these differences. The results also indicated that prolonged daily practice (>4 hours), playing chords forcefully, eagerness about practice, and nervous traits were found to contribute to the development of PRMDs in these pianists. Hand size was, on the other hand, not a significant risk factor of PRMDs.


De Jure ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Daniel Haman ◽  
◽  
◽  

The difference between intent (dolus) and negligence (culpa) was rarely emphasized in codified medieval laws and regulations. When compared to the legal statements related to intent, negligence was mentioned even more rarely. However, there are some laws that distinguished between the two concepts in terms of some specific crimes, such as arson. This paper draws attention to three medieval Slavic legal documents – the Zakon Sudnyj LJudem (ZSLJ), the Vinodol Law and the Statute of Senj. They are compared with reference to regulations regarding arson, with the focus being on arson as a crime committed intentionally or out of negligence. The ZSLJ as the oldest known Slavic law in the world shows some similarities with other medieval Slavic legal codes, especially in the field of criminal law, since most of the ZSLJ’s articles are related to criminal law. On the other hand, the Vinodol Law is the oldest preserved Croatian law and it is among the oldest Slavic codes in the world. It was written in 1288 in the Croatian Glagolitic script and in the Croatian Chakavian dialect. The third document – the Statute of Senj – regulated legal matters in the Croatian littoral town of Senj. It was written in 1388 – exactly a century after the Vinodol Law was proclaimed. When comparing the Vinodol Law and the Statute of Senj with the Zakon Sudnyj LJudem, there are clear differences and similarities, particularly in the field of criminal law. Within the framework of criminal offenses, the act of arson is important for making a distinction between intent and negligence. While the ZSLJ regulates different levels of guilt, the Vinodol Law makes no difference between dolus and culpa. On the other hand, the Statute of Senj strictly refers to negligence as a punishable crime. Even though the ZSLJ is almost half a millennium older than the Statute of Senj and around 400 years older than the Vinodol Law, this paper proves that the ZSLJ defines the guilt and the punishment for arson much better than the other two laws.


2021 ◽  
Vol 2 (4) ◽  
pp. 91-101
Author(s):  
Saleha Ilhaam

The term strategic essentialism, coined by Spivak, is generally understood as “a political strategy whereby differences (within Group) are temporarily downplayed, and unity assumed for the sake of achieving political goals.” On the other hand, essentialism focuses that everything in this world has an intrinsic and immutable essence of its own. The adaption of a particular “nature” of one group of people by way of sexism, culturalization, and ethnification is strongly linked to the idea of essentialism. Mulk Raj Anand’s Bakha is dictated as an outcast by the institutionalized hierarchy of caste practice. He is essentialized as an untouchable by attributing to him the characteristic of dirt and filth. However, unlike other untouchables, Bakha can apprehend the difference between the cultured and uncultured, dirt and cleanliness. Via an analysis of Anand’s “Untouchable,” the present article aims to bring to the forefront the horrid destruction of the individual self that stems from misrepresentations of personality. Through strategic essentialism, it unravels Bakha’s contrasting nature as opposed to his pariah class, defied by his remarkable inner character and etiquette. The term condemns the essentialist categories of human existence. It has been applied to decontextualize and deconstruct the inaccurately essentialized identity of Bakha, which has made him a part of the group he does not actually belong to.


2021 ◽  
Vol 15 (2) ◽  
Author(s):  
Hanah Khoirunnisa ◽  
Mardi Wibowo ◽  
Wahyu Hendriyono ◽  
Khusnul Setia Wardani

The flight test of N219 Amphibious aircraft will be targeted in 2003/2024. For flight tests, these aircraft need a seaplane dock. One of the potential locations for the seaplane dock is Panjang Island at Seribu Islands. This study aims to know the characteristic of hydrodynamic and wave conditions and to determine whether Panjang Island is suitable for the seaplane dock. This study uses a modeling method with MIKE 21 FM HD-SW module and MIKE 21 Boussinesq Wave (BW)  module. The bathymetry data were obtained from the Indonesian Navy Hydrographic and Oceanographic Center (Pushidrosal), tide data is generated from Tide Model Driver (TMD), wave and wind data from ECMWF. The result of surface elevation validation between hydrodynamic modeling and TMD is 92%. During the west monsoon and spring conditions, the difference in the largest and lowest current velocity is quite large (0.018-0.199 m/s), on the other hand, when the tides are in neap conditions (0.008-0.144 m/s). Meanwhile, during the east monsoon and spring conditions, the difference in the largest and lowest current velocities is quite large (0.02-0.193 m/s), on the other hand, when the tides are in neap conditions (0.008-0.146 m/s). The maximum wave height resulting from the 50-year return period waveform modeling between 1.139 - 1.474 m. Meanwhile, the significant wave heights between 0.679 - 0.741 with a significant wave period of 13.45 seconds. In general, the current and wave conditions of the two locations are suitable for the construction of the seaplane dock, except that the dominant wave heights are still above the requirements.


2017 ◽  
Vol 56 (1-4) ◽  
Author(s):  
Anikó Polgár

This study is dealing with two Hungarian translations of Euripides’ Medea. The translation made by Grácia Kerényi was produced in the second half of the 20th century, whereas the version by Zsuzsa Rakovszky was published at the beginning of the 21st. The difference between the translations regarding their textual strategies, the professional background of the translators and the final goal of the works is abysmal. Grácia Kerényi was an expert of ancient literatures, her translation was published in the official and renowned collection of Euripides’ work, Zsuzsa Rakovszky on the other hand translates predominantly from English, and her version was inspired by the request of the theatre. The study contains three parts: in the first the author analyses Kerényi’s Medea in the context of the philological reconstruction, in the second, the author examines the same text modified and revised by Fruzsina Magyar, who was the dramatic advisor of the theatre performance in Szolnok, and the third part reflects on the problems of validity, poetical force and immediacy in the translation of Zsuzsa Rakovszky.


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